Purchase this article with an account.
Miranda Scolari, John T. Serences; Assessing sensory gain during the maintenance of information in working memory. Journal of Vision 2009;9(8):594. doi: 10.1167/9.8.594.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Visual Working memory (WM) involves an encoding stage, in which a perceptual representation of a visual stimulus (e.g., 90° line) is consolidated into a WM representation, and a maintenance stage, in which this representation is held in memory during a delay period. While the mechanisms in early visual cortex that support encoding are relatively well understood, much less is known about how activity in these same areas contributes to the maintenance of a mnemonic representation during the delay period. Here we present a psychophysical method designed to examine how gain is applied to the sensory neurons that represent the remembered stimulus during the delay period of a difficult WM task. On each trial, we briefly presented a to-be-remembered oriented stimulus (the sample stimulus). On 64% of the trials, a test item which either matched the sample or differed by ±10° (a mismatch) appeared after a 1200ms delay. Importantly, the relatively high frequency of these trials induced an expectation for a WM trial. On the remaining 36% of the trials we probed the distribution of neural gain in early visual cortex after a variable delay (400ms or 1200ms) by measuring contrast detection thresholds for a single orientated stimulus rotated by 0°, ±10°, or ±20° with respect to the sample. We found that the shape of the gain profile differed between the short and long delay periods, suggesting that subjects may not maintain a static representation of the sample. Furthermore, the shape of the gain profile differed across subjects, suggesting the existence of individual differences in the way people represent and maintain items in visual working memory.
This PDF is available to Subscribers Only